FIG. 1 is a block diagram showing a magnetic detector circuit of a conventional magnetic detection type pointing device. A detecting section 1 includes four magnetic sensors (such as Hall elements, semiconductor magneto-resistive elements, thin-film magneto-resistive elements and GMR elements) 11, and the Hall elements 11 are placed symmetrically two by two on the X and Y axes. A magnet is placed near the center of the four Hall elements 11 symmetrically disposed on the X and Y axes. Because of the variations in the magnetic flux density due to the movement of the magnet, the output voltages of the Hall elements 11 vary.
Differential amplifiers 2 differentially amplify the outputs of the Hall elements 11 on the X and Y axes, respectively. The output is adjusted to zero when the magnetic flux density in the Z direction is symmetry with respect to the origin O, that is, when the magnetized direction of the magnet is in the vertical direction. As the magnet moves, the differential amplifiers 2 produce outputs, and a detection control section 3 converts the outputs (analog values) in the X coordinate value and Y coordinate value, which are output through an output control section 4.
As a concrete example of a small pointing device used by a mobile phone, a device is known which employs a scheme placing a magnet on a key mat. Such devices based on the method enable miniaturization among the currently proposed ideas (see Japanese patent application laid-open No. 2002-150904, for example).
As a contact type pointing device, a device is common which forms on a printed board two pairs of comb electrodes, and depresses them via a conductive rubber from the top to vary the current-passing state, thereby outputting coordinate values in digital values.
However, in small mobile electronic equipment such as a mobile phone, further reductions in size and height of the components are required to satisfy mutually contradictory needs of reducing the size and improving the function of the electronic equipment in its entirety. In addition, further improvement in operating feelings of the magnetic detection type pointing device is expected.
Furthermore, as for the foregoing publication, since the magnet is magnetized in the vertical direction, the magnetic flux density that leaks out is large so that when a magnetic card is brought close to it, a problem of losing the information of the magnetic card is likely to occur.
Moreover, since the input is made by depressing the conductive rubber in the contact type pointing device, degradation of the conductive rubber involved in repetitive input and the like is unavoidable, which presents a problem of reducing the life.
The present invention is implemented to solve the foregoing problems. Therefore it is an object of the present invention to provide a pointing device that can reduce the size and height, and provide a good operating feeling, and that has small external leakage of the magnetic flux density, and has a long product life.